Semiconductor light emitting devices, such as Light Emitting Diodes (LEDs) or laser diodes, are widely used for many applications. As is well known to those having skill in the art, a semiconductor light emitting device includes a semiconductor light emitting element having one or more semiconductor layers that are configured to emit coherent and/or incoherent light upon energization thereof. It is also known that the semiconductor light emitting element generally is packaged to provide external electrical connections, heat sinking, lenses or waveguides, environmental protection and/or other functions for the semiconductor light emitting device. Packaging may be provided, at least in part, by at least partially surrounding the semiconductor light emitting device with a dome-shaped transparent plastic shell.
For example, it is known to provide a two-piece package for a semiconductor light emitting device wherein the semiconductor light emitting element is mounted on a substrate of, for example, alumina, aluminum nitride and/or other materials, which include electrical traces thereon, to provide external connections for the semiconductor light emitting element. A second substrate, which, for example, may be silver plated copper, is mounted on the first substrate, for example using glue, surrounding the semiconductor light emitting element. A lens may be placed on the second substrate over the semiconductor light emitting element. Light emitting diodes with two-piece packages as described above are described in application Ser. No. 10/446,532 to Loh, entitled Power Surface Mount Light Emitting Die Package, filed May 27, 2003, assigned to the assignee of the present invention, the disclosure of which is hereby incorporated herein by reference in its entirety as if set forth fully herein.
It is often desirable to incorporate phosphor into a semiconductor light emitting device, to enhance the emitted radiation in a particular frequency band and/or to convert at least some of the radiation to another frequency band. Phosphors may be included in a semiconductor light emitting device using many conventional techniques. In one technique, phosphor is coated inside and/or outside the plastic shell. In other techniques, phosphor is coated on the semiconductor light emitting device itself, for example using electrophoretic deposition. In still other techniques, a drop of a material such as epoxy that contains phosphor therein may be placed inside the plastic shell, on the semiconductor light emitting device and/or between the device and the shell. This technique may be referred to as a “glob top”. The phosphor coatings may also incorporate an index matching material and/or a separate index matching material may be provided. LEDs that employ phosphor coatings are described, for example, in U.S. Pat. Nos. 6,252,254; 6,069,440; 5,858,278; 5,813,753; 5,277,840; and 5,959,316.
Unfortunately, the packaging for a semiconductor light emitting device may be costly and, in some cases, more costly than the semiconductor light emitting element itself. Moreover, the assembly process also may be costly, time consuming and/or subject to failures.